Cryopreservation of single human spermatozoa

A procedure is described that allows cryopreservation and efficient post-thaw recovery of either a single or a small group of human spermatozoa. This is achieved by injecting them into cell-free human, mouse or hamster zonae pellucidae before the addition of cryoprotectant. The method involves a combination of physical micromanipulation procedures and glycerol-mediated cryoprotection. Zonae were tracked by positioning them in straws between two small air bubbles prior to freezing. Spermatozoa from poor specimens were cryopreserved and their fertilizing ability after thawing was compared with that of fresh spermatozoa from fertile men. Human eggs used for fertilization testing were either 1 day old or in-vitro matured. Only 2% of the frozen zonae were lost and >75% of spermatozoa cryopreserved in this manner were recovered and prepared for intracytoplasmic sperm injection. The feasibility of cryopreserving a single spermatozoon was assessed. Fifteen motile spermatozoa were frozen in 15 zonae, of which 14 were recovered after thawing. Ten were injected into spare eggs, of which eight became fertilized. Spermatozoa recovered mechanically from human zonae fertilized the same proportion of oocytes as fresh fertile control spermatozoa. The recovery and fertilization rates with spermatozoa frozen in animal zonae were 87 and 78% respectively. The fertilization rate was marginally higher (P < 0.05) than that for spermatozoa frozen in human zonae, perhaps because the latter may have acrosome reacted more frequently. The zona pellucida appears to be an ideally suited sterile vehicle for storage of single spermatozoa.     

An efficient method for solving elliptic boundary element problems with application to the tokamak vacuum problem

A method for regularizing ill-posed Neumann Poisson-type problems based on applying operator transformations is presented. This method can be implemented in the context of the finite element method to compute the solution to inhomogeneous Neumann boundary conditions; it allows to overcome cases where the Neumann problem otherwise admits an infinite number of solutions. As a test application, we solve the Grad–Shafranov boundary problem in a toroidally symmetric geometry. Solving the regularized Neumann response problem is found to be several orders of magnitudes more efficient than solving the Dirichlet problem, which makes the approach competitive with the boundary element method without the need to derive a Green function. In the context of the boundary element method, the operator transformation technique can also be applied to obtain the response of the Grad–Shafranov equation from the toroidal Laplace n=1 response matrix using a simple matrix transformation.     

T 2 relaxometry measurements in low spatial frequency brain regions differ between fast spin-echo and multiple-echo spin-echo sequences

Object

Dual-echo fast spin-echo (FSE) sequences are used in T ₂ relaxometry studies of neurological disorders because of shorter clinical scanning times and protocol simplicity. However, FSE sequences have possible spatial frequency-dependent effects, and derived T ₂ values may include errors that depend on the spatial frequency characteristics of the brain region of interest.

Materials and methods

Dual-echo FSE and multi-echo spin-echo (MESE) sequences were acquired in nine subjects. The T ₂ decay curves for FSE and MESE sequences were estimated and percent error maps were generated. T ₂ error values were obtained along each patient’s corticospinal tract (CST). Whole-brain white matter (WM) and gray matter (GM) T ₂ error values were also obtained. The paired t test was performed to evaluate differences in T ₂ values in the CST between FSE and MESE sequences.

Results

Histograms of error values in CST and in whole-brain WM and GM structures revealed systematic errors in FSE sequences. Significant differences (P < 0.001) in CST T ₂ values were also observed between FSE and MESE sequences.

Conclusion

Our findings indicate that T ₂ values derived from FSE sequences are prone to large errors, even in low spatial frequency regions such as the CST, when compared to MESE sequences. Future studies should be aware of this limitation of FSE sequences.     

Computer response time measurements of mood,fatigue and symptom scale items: Implications for scale response time uses

Response time (RT) to computer-administered questionnaire items were measured in two studies to evaluate how useful it might be in various research areas. These studies had different start-of-day times and each had two exercise levels. Thirty subjects were tested over two continuous 20 hour days (CW1 and CW2) with three hours of nap time allowed between days. The scales analyzed were the Vigor and Fatigue scales of the Profile of Mood States (POMS), a symptom checklist, a Guttman type fatigue scale, and a Negative and Positive mood scale. Response time to most scales were faster on CW2, whereas the symptom, negative mood and fatigue scales increased and the vigor and positive scale values were lower CW2. There were no differences between exercise levels or start time studies in scale RT. Reaction time on a simple psychomotor task was significantly slower on CW2, but was not correlated with any scale RT either day, indicating that response speed was not involved in scale RT. Also, there were no significant correlations between reading speed or reading grade level with scale RTs. Mean POMS Fatigue scale RT was highly correlated with the mean scale value both days, showing slower RT with higher fatigue scale values. The Positive Scale took longer than the Negative Scale, and the POMS Vigor took longer than Fatigue both days showing some support for the theory that moods congruent with the present state are more prominent in memory as indicated by faster FT. The most complex scale (Guttman) had the longest RT while the most simple (dichotomous) had the shortest RT. Scale RT showed some usefulness as a measure in a variety of research areas.     

Preimplantation genetic analysis of translocations: case-specific probes for interphase cell analysis

Carriers of balanced translocations show an increased risk of infertility and spontaneous abortions, because of errors in gametogenesis, and constitute a significant fraction of patients seeking assisted reproduction. The objective of this study was to design approaches for preimplantation diagnosis of chromosome translocations and to apply such techniques to the selection of chromosomally normal or balanced embryos prior to their transfer to the mother's womb. Three slightly different approaches were assessed by means of chromosome-specific, non-isotopically labeled DNA probes and an assay based on fluorescence in situ hybridization- to score and characterize chromosomes in single blastomeres biopsied from embryos on their third day of development. The three approaches were used for preimplantation genetic diagnosis involving four couples who had enrolled in our IVF program and in which one of the partners was a carrier of one of the following translocations: 46,XX,t(12;20)(p 13.1 ;q 13.3), 46,XY,t(3;4) (p24;p15), 45,XY,der(14;15)(10q;10q), and 46,XY,t(6;11) (p22.1;p15.3). A total of 33 embryos were analyzed, of which 25 (75.8%) were found to be either unbalanced or otherwise chromosomally abnormal. Only a single embryo could be transferred to patients A and D, whereas three embryos were transferred to patient B in a total of two IVF cycles. Transfer of two embryos to patient C resulted in an ongoing pregnancy. Re-analysis of non-transferred embryos with additional probes confirmed the initial results in 95% (20/21) of the cases. In conclusion, case-specific translocation tests can be applied to any translocation carrier for the selection of normal or chromosomally balanced embryos prior to embryo transfer. This is expected significantly to increase the success rates in IVF cycles of translocation carriers, while preventing the spontaneous abortion or birth of abnormal offspring.     

Automatic authentication using rough set-based technique and fuzzy decision

This study introduced an automatic authentication technique for checking the genuineness of a vehicle.The rough set-based technique was used to handle the uncertainty arisen from artifacts in the acquired images imprinted on a vehicle.However,it has been proved to be NP-hard to find all reductions and the minimal reduction,and generally different heuristic algorithms were used to find a set of reductions and the Gaussian distribution was used to describe the uncertainty to achieve the minimal reduction.On the basis of inductive logic programming,the technique can distinguish between two similar images,as is superior to the conventional pattern-recognition technique being merely capable of classifier.Furthermore,it can avoid some failures of the technique based on the correlation coefficient to authenticate binary image.The experiments show an accuracy rate close to 93.2%.     

Study of Fuel Ratios on the Fusion Reactivity in an Inertial Electrostatic Confinement Device Using a Residual Gas Analyzer

Gridded Inertial Electrostatic confinement (IEC) devices are of interest due to their flexibility in burning advanced fuels, their tuning ability of the applied voltage to the reaction cross-section. Although this device is not suitable for power production in its present form, it does have several near term applications. The number of applications of this device increases with increasing fusion reactivity. These devices are simple to operate but are inherently complicated to understand and an effort to incrementally understand the device to improve its operational efficiency is underway at University of Wisconsin, Madison. Of all the parameters under study we are focusing on the effects of flow rate and flow ratio on the fusion reactivity in the present paper. Experiments were conducted to understand the influence of fuel flow ratio on the fusion reactions. The residual gas analyzer (RGA) was used to study the impurity concentration as the flow ratio was changed. It was observed that the higher flow rate resulted in reduced impurity levels and hence an increase in fusion rate. Several different species of gases were detected, some of these molecules formed inside the RGA analyzer. The flow ratio scan revealed that the optimum mixture of D₂ with ³He to be D₂:³He::1:2 for maximum D–³He fusion rate.     

Combined activation methods for proton-exchange membrane fuel cells

Activating a PEM fuel cell by combining various activation methods could achieve a better performance than if only a single method was used. The combination of the following activation methods, (a) elevated temperature and pressure, (b) hydrogen evolution, and (c) CO oxidative stripping, was studied. First, any of these activation methods could largely increase the fuel cell performance more than a traditional break-in procedure. Second, the effectiveness of the individual methods was in the following sequence: (a) > (b) ≥ (c). Third, if method (a) was carried out after either method (b) or (c), the fuel cell performance could be further increased; but the final performance would be similar to that from just carrying out method (a) itself. Fourth, carrying out either method (b) or (c) after method (a) could further increase the fuel cell performance.